Iteration Algorithm of Reliability Evaluation for Medium Voltage System

The fault-spreading algorithm is often used in the reliability evaluation of medium-voltage distribution networks. However, there exist many redundant searches in the fault- spreading algorithm, which lower the calculation efficiency. To improve the search performance, an iteration algorithm is presented in this paper. This algorithm first establishes a switch- layer tablet before fault enumeration. In the tablet, the backward information, for example, load of the present switch can be partially obtained from the switches in the backward layer, which spare much time for backward search. Secondly, by using the information in the known fault sequences and in the switch- layer tablet, based on the switch-fixing information of the fault point and its forward point, various fault modes and load- classification can be derived without forward searches. This algorithm has been applied to reliability evaluation of the test system RBT-BUS6, RBT-BUS2, and a practical system. The test results have shown that the algorithm is correct and effective. Finally, the time complexity degree analysis has also shown that this algorithm is more superior to the fault-spreading one..